1. Field of the Invention
The present invention relates to a pump with a control assembly for controlling activation and deactivation of an impeller unit of the pump, more particularly to one which has a control assembly that incorporates a ripple-effect removing valve so as to correctly deactivate the impeller unit upon detecting that the pressure of fluid at an outlet of the pump reaches a predetermined value.
2. Description of the Related Art
FIGS. 1 and 2 illustrate a conventional rotary pressurizing pump 1 with a pressure detecting device 3 mounted thereon for controlling activation and deactivation of a rotary impeller unit 15 of the pump 1. The rotary pressurizing pump 1 includes a hollow body 11 having an inlet 13 and an outlet 12 which is formed in an upper portion of the hollow body 11. The impeller unit 15 is disposed in the hollow body 11 for increasing pressure of fluid that flows from the inlet 13 to the outlet 12. The hollow body 11 is further formed with a threaded mounting hole 14 in the upper portion and adjacent to the outlet 12. The fluid pressure at the mounting hole 14 is substantially equal to the fluid pressure at the outlet 12. The pressure detecting device 3 is mounted on the hollow body 11 at the mounting hole 14 for detecting the fluid pressure at the outlet 12. As shown, a non-return valve 2 is mounted on the hollow body 11 at the inlet 13 to permit fluid flow in a direction toward the inlet 13 while preventing fluid flow in an opposite direction out of the inlet 13.
The pressure detecting device 3 includes a housing 36 having a lower threaded end 311 mounted threadedly in the threaded mounting hole 14 of the hollow body 11. A switch assembly 34, which is connected electrically to the impeller unit 15 of the pump 1, is provided in the housing 36. The housing 36 has a lower chamber 38 which is fluidly communicated with the mounting hole 14 to permit the flow of fluid from the mounting hole 14 to the lower chamber 38 in an upward direction. A diaphragm unit 32 is supported on a diaphragm seat 321 and is disposed horizontally in the lower chamber 38. The diaphragm unit 32 senses the pressure of the fluid entering the lower chamber 38 and bulges accordingly due to the pressure of the fluid. An actuator 331 is mounted on the diaphragm unit 32 and is operably connected to the switch assembly 34, which includes a horizontal linking plate 342, a curved spring plate 344, an upright linking rod 345, a spring-loaded switch member 346 and an electrical contact 35. In detail, the actuator 331 has an upper end abutting against a portion of the horizontal linking plate 342, which has one end connected to a first end of the curved spring plate 344. The spring plate 344 has a second end connected to the upright linking rod 345 which, in turn, is connected to a lower end of the spring-loaded switch member 346. The switch member 346 is normally biased upwardly to contact the electrical contact 35 so as to establish electrical connection between the switch assembly 34 and the impeller unit 15 of the pump 1. The pressure detecting device 3 further includes a biasing spring 336 mounted on a support 333 and disposed in the housing 36 above the horizontal linking plate 342. A movable pressing board 335 is disposed on the biasing spring 336, and a regulating screw member 334 is mounted on the pressing board 335. The regulating screw member 334 is operable to move the pressing board 335 downwardly to compress the biasing spring 336 or upwardly to relax the biasing spring 336 so as to preset the biasing force of the latter. The biasing spring 336 has a lower end provided with an abutment member 332 that abuts against the horizontal linking plate 342 due to the biasing force of the spring 336. Therefore, the biasing force of the spring 336 can be preset for pushing the diaphragm unit 32 to resist bulging thereof until the pressure of the fluid reaches the predetermined value.
Referring to FIG. 3, once the pressure of the fluid entering the lower chamber 38 reaches the predetermined value, the diaphragm unit 32 bulges upwardly to move the actuator 331 and the horizontal linking plate 342 upwardly against the biasing force of the spring 336. At this time, the curved spring plate 344 moves to pull the upright linking rod 345 and the spring-loaded switch member 346 downwardly so that the switch member 346 is not in contact with the electrical contact 35 and so that the electrical connection between the switch assembly 34 and the impeller unit 15 is broken. The impeller unit 15 is deactivated to stop pressurizing of the fluid at this time. Therefore, the pressure of fluid will not be excessive so as to avoid damaging the pump.
The pressure detecting device 3 achieves the purpose of automatically turning-off the impeller unit 15 of the pump 1 upon detecting that the pressure of fluid at the outlet 12 reaches a predetermined value. It is noted that incorrect action of the diaphragm unit 32 usually occurs due to the ripple-effect of the fluid entering into the lower chamber 38. That is to say, undesired bulging of the diaphragm unit 32 might occur due to the ripple-effect of the fluid, thereby deactivating the impeller unit 15 before the pressure of the fluid reaches the predetermined value. It is thus desired to provided a ripple-effect removing valve between the pressure detecting device 3 and the mounting hole 14 of the hollow body 1 to eliminate the possibility of incorrect action of the diaphragm unit 32 due to the ripple-effect of the fluid.